北京某染料厂污染地块土壤和地下水6种氯苯类化合物的分布特征及迁移转化分析

针对染料化工企业用地存在多种氯苯类化合物污染的问题，以北京某染料厂污染地块为研究对象，采集并测定土壤样品260个、地下水样品6个，研究了地块包气带和饱和带中6种氯苯类化合物的分布特征，分析了6种物质的来源与迁移过程。结果表明，6种氯苯类化合物主要分布在生产区及污水处理区等重污染区的包气带中，低氯苯类化合物遍布地下水中。推断四氯苯、五氯苯和六氯苯主要由生产原料(二氯苯和三氯苯)在高温等工艺条件下发生氯化反应转化而成，而氯苯是由深层厌氧环境中的CBs经微生物还原脱氯生成。氯苯自深层厌氧区迁移扩散，部分向上扩散进入包气带再挥发至空气中；其它5种污染物在重污染区进入包气带，主要受淋溶以及重力作用向下迁移，汇集于包气带的黏粉~粉黏层，其中的二氯苯和三氯苯穿透包气带进入地下水并扩散至整个厂区。本研究结果可为染料化工污染地块的调查及修复工程提供参考。

Distribution,migration and transformation of six chlorobenzene compounds in soil and groundwater of a dye factory in Beijing

Aiming at the pollution problem of a variety of chlorobenzene compounds in the land used by dye chemical enterprises, taking a dye contaminated site in Beijing as the research object. A total of 260 soil samples and 6 groundwater samples were collected and analyzed. The distribution of six chlorobenzene compounds in the vadose zone and saturation zone of the site were investigated, and the source and migration process of the six substances were analyzed. The results showed that six chlorobenzene compounds were mainly distributed in the vadose zone of the heavily polluted areas, such as the production area and the sewage treatment area. Additionally, the low chlorobenzene compounds were found all over the groundwater. It was inferred that tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene were mainly produced by chlorination of raw materials (dichlorobenzene and trichlorobenzene) under high temperature and other process conditions, while chlorobenzene was generated by anaerobic microbial reduction dechlorination of CBs in deep anaerobic zone. Chlorobenzene migrates and diffuses from the deep anaerobic zone, and part of it diffuses upward into the vadose zone and then volatilizes into the air. The other five pollutants enter the vadose zone of the heavily polluted area, migrate downward mainly by leaching and gravity, and collect in the sticky powder ~ powder sticky layer of the vadose zone. Particularly, dichlorobenzene and trichlorobenzene penetrate the vadose zone and spread throughout in the groundwater of the site. The results of this study can provide a reference for the investigation and remediation of dye chemical contaminated sites.